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LM80 lockup issue

Nick Dai
Expert 4240 points
Other Parts Discussed in Thread: LM80, LM96080

Hi Team,

  My customer met several LM80 I2C lockup issue.(SDA lockup),and there are some questions for this issue,please help to check.

1.In I2C specification,when SDA stuck,it should can be recover when master send nine clocks pulse,but i seen in another post that LM80 can't support this as below link.

e2e.ti.com/.../538034

But my customer found the SDA was recovered after nine clocks,but stuck again as below figure.

   Could you help feedback what's the correct way to recover I2C of LM80 when SDA stuck?

Best Regards,

Nick Dai

  • 0
    TI__Genius 16890 points

    Hi Nick,

    They can reset the LM80 to the power on state by pulling the NTEST_IN/Reset_IN pin low for at least 50ns. 

    Another option is to replace the LM80 with the LM96080.  It is pin to pin operation compatible and has the timeout function.

    An observation: why does the clock have an 80% duty cycle?  Clocks should have a 50% duty cycle.  This could possibly be causing a timing issue that causes it to lock up in the first place.

    Mike